The conceptual foundation of active suspension is "Skyhook theory," which posits that an ideal suspension would maintain a stable vehicle posture as if suspended from an imaginary hook in the sky. This theoretical state would keep the vehicle at a constant altitude above sea level, unaffected by road irregularities or weight transfer.
In practice, active suspensions use some type of actuator to raise and lower the chassis. True active suspensions can independently raise and lower the chassis at each wheel, whereas semi-active suspensions only vary shock absorber firmness to match changing road or dynamic conditions.
Active suspensions use separate actuators which can exert an independent force on the suspension to improve the riding characteristics. The drawbacks of this design are high cost, added complication and mass of the apparatus, and the need for frequent maintenance on some implementations.
Hydraulically actuated suspensions are controlled with the use of hydraulics. The first example appeared in 1954, with the hydropneumatic suspension developed by Paul Magès at Citroën.
Colin Chapman developed the original concept of computer management of hydraulic suspension in the 1980s to improve cornering in racing cars. Lotus fitted and developed a prototype system to a 1985 Excel with electro-hydraulic active suspension.
By calendar year:
1954: Citroën Traction Avant 15-6H:, self-leveling Citroën hydropneumatic suspension on rear wheels. 1955: Citroën DS, self-leveling Citroën hydropneumatic suspension on all four wheels. 1967: Rolls-Royce Silver Shadow Partial load bearing hydropneumatic suspension on all four wheels. 1975: Mercedes Benz 450 SEL 6.9 Hydropneumatic suspension on all four wheels. 1983: Toyota Soarer: world first Electronically controlled (TEMS) that used a shock absorber control actuator (spring constant, variable attenuation force) installed 1985: Nissan introduced ultrasound semi-active suspension sensing "Super Sonic Suspension" optionally on the Cedric, Gloria and Nissan Laurel that integrated actuators inside the MacPherson struts on the front and rear suspension. 1986: Jaguar XJ40, self-leveling suspension. 1986: Mercedes Benz W126 Hydropneumatic suspension on all four wheels with electronically controlled adaptive damping as an option on the LWB v8 models 1987: Mitsubishi Galant (sixth generation) - features Active Controlled Suspension (Dynamic ECS). 1989: Citroën XM - self-levelling, semi-active Hydractive on all four wheels with automatically adjusted spring rates and dampeners. 1989: Mercedes Benz R129 Partial load bearing hydropneumatic suspension with automatically adjusted spring rates and dampers as an option (ADS) 1990: Infiniti Q45 and Nissan President "Full-Active Suspension (FAS)", active suspension system 1990: Toyota Celica (ST183) Active Sports with fully Hydropneumatic active suspension and 4WS GT-R with Toyota Electronic Modulated Suspension (TEMS) semi-active suspension 1991: Toyota Soarer (UZZ32) Fully active computer-controlled Hydropneumatic suspension with 4WS 1992: Citroën Xantia VSX - self-levelling, semi-active Hydractive 2 on all four wheels, with automatically adjusted spring rates and dampeners. 1993: Cadillac, several models with RSS road sensing suspension. 1994: Toyota Celsior introduced first Skyhook air suspension 1994: Citroën Xantia Activa - self-levelling, fully active Hydractive on all four wheels with hydraulic anti-roll bars and automatically adjusted spring rates and dampeners. 1998: Land Rover Discovery series 2 - Active Cornering Enhancement; an electronically controlled hydraulic anti-roll bar system was fitted to some versions, which reduced cornering roll. 1999: Mercedes Benz C215 Self leveling fully active hydraulic Active body control. 2000 Citroen C5 Hydractive 3 or Hydractive 3+ 2002: Cadillac Seville STS, first MagneRide 2004: Volvo S60 R and V70 R (Four-C, a short name for "Continuously Controlled Chassis Concept", semi-active) 2006 Citroen C6 - Hydractive 3+ 2010: Alfa Romeo MiTo Cloverleaf (DNA System based on Maserati's Skyhook technology) 2012: Jaguar XF Sportbrake, self-leveling air suspension. 2013: Mercedes Benz W222: Optional Magic body control. 2013: Volkswagen Mk7 Golf R User-Selectable Electronically Controlled Shock Dampening (Dynamic Chassis Control (DCC)) 2019: Toyota Avalon Touring model (Adaptive Variable Suspension (AVS)) 2025: Nio ET9 (SkyRide fully active suspension) 2025: Lincoln, as of 2025 all vehicles from Lincoln Motor Company offer active suspension.
Toyota Active Control Suspension Hydropneumatic suspension Active Body control
Nye, Doug (1992). History of the Grand Prix Car: 1966-91. Hazleton Publishing. ISBN 0-905138-94-5. Cox, Ronald W. (1986). Electronics Developed for Lotus Active Suspension Technology. US: General Motors. Archived from the original on 2013-06-17. Retrieved 2013-01-17.